1. Field of the Invention
The present invention relates to a droplet discharging head and inkjet recording apparatus, and more particularly, to a structure of a droplet discharging head that is suitable for increasing the density of nozzles (droplet discharge ports), and to an inkjet recording apparatus using same.
2. Description of the Related Art
An inkjet recording apparatus is an apparatus for forming images by means of ink dots, by causing ink to be discharged from a recording head comprising nozzles for discharging ink, in accordance with a print signal, thereby causing ink droplets to land on a recording medium, such as recording paper, or the like, while moving the recording medium relatively with respect to the recording head. In recent years, recording heads have been proposed wherein pressure chambers connected to nozzles are disposed in a three-dimensional fashion, by means of a layered structure, in order to achieve higher density of nozzles in order to respond to high levels of resolution in images (see Japanese Patent Application Publication No. 2001-146010, and Japanese Patent Application Publication No. 2001-260347).
In Japanese Patent Application Publication No. 2001-146010, a head unit consisting of pressure chambers and piezoelectric elements has a structure which is layered in two levels, an upper and a lower level, a common nozzle plate being provided in the lower first-level head unit only, and ink inside the pressure chambers in the upper level (second-level head unit) being discharged from nozzles via connecting holes passing through the first-level head unit.
In Japanese Patent Application Publication No. 2001-260347, first pressure chambers corresponding respectively to every other nozzle of a plurality of nozzles arranged in a row, and second pressure chambers corresponding to the remaining nozzles are disposed in a layered fashion, and two piezoelectric actuators corresponding to two pressure chambers are layered respectively thereon, via a rigid plate.
However, in the structures proposed in the prior art, since the distance from the pressure chamber to the nozzle differs between the upper level and the lower level, then the discharge performances are different in the respective layers. Therefore, if image recording is carried out using a convention recording head of this kind, unevenness of streaking may arise in the image, in accordance with the layers in which the pressure chambers are positioned.